Put your cell phone down — and keep it away from your pillow, the California Department of Public Health is advising.

Smartphone use continues to increase in the U.S., especially among children, and the health department said some people and health professionals have concerns about the radio frequency energy emitted from cell phones. The scientific community has not reached a consensus on the risks of cell phone use, but the health department said research suggests long-term, extensive use may affect health.

“We know that simple steps, such as not keeping your phone in your pocket and moving it away from your bed at night, can help reduce exposure for both children and adults,” said Dr. Karen Smith, state public health officer. Smartphones emit radio frequency energy when they send signals to and receive them from cell towers.

“Children’s brains develop through the teenage years and may be more affected by cell phone use,” Smith said. “Parents should consider reducing the time their children use cellphones and encourage them to turn the devices off at night.”

She also suggested keeping the phone away from the body and keep the phone away from the bed at night.